182
FXUS66 KPQR 030542 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1042 PM PDT WED SEP 2 2026
AVIATION AND MARINE DISCUSSION UPDATED...
SYNOPSIS
A FRONTAL SYSTEM WILL BRING WIDESPREAD RAIN, BREEZY
WINDS FROM THE SOUTH, AND A 15-20% CHANCE FOR THUNDERSTORMS
TODAY. RAIN CONTINUES TOMORROW WITH A 20-30% CHANCE FOR
THUNDERSTORMS. ANY PASSING THUNDERSTORMS MAY PRODUCE LIGHTNING,
HEAVY RAIN, GUSTY ERRATIC WINDS, SMALL HAIL, AND/OR A FUNNEL
CLOUD. CHANCES FOR LINGERING SHOWERS CONTINUE THROUGH THE
WEEKEND WITH COOLER THAN AVERAGE TEMPERATURES. DRIER CONDITIONS
EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
RADAR, SATELLITE,
AND SURFACE OBSERVATIONS AS OF LATE WEDNESDAY MORNING DEPICTS
WIDESPREAD RAIN ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON
AS OUR FIRST FALL-LIKE FRONTAL SYSTEM PUSHES THROUGH THE
REGION. AS THE FRONT SWINGS THROUGH, EXPECT RAIN TO PERSIST
TODAY ALONG WITH BREEZY WINDS FROM THE SOUTH/SOUTHWEST. BUOY
OBSERVATIONS HAVE BEEN SHOWING WIND GUSTS PEAKING AROUND 35-45
MPH OVER THE MARINE WATERS WITH THE FRONTAL PASSAGE, SO EXPECT
SIMILAR GUSTS ALONG THE IMMEDIATE COAST. AS THE FRONT MOVES
INLAND, WE'LL ALSO SEE WINDS INCREASE ALONG THE I-5 CORRIDOR AND
INTERIOR VALLEYS, BUT NOT AS STRONG AS THE COAST. PRESSURE
GRADIENTS ARE NOT LOOKING AS TIGHT, SO WE'LL LIKELY (80% CHANCE)
EXPERIENCE PEAK GUSTS BETWEEN 20-35 MPH FOR INTERIOR LOCATIONS.
CAN'T RULE OUT A LOW CHANCE (10%) FOR ISOLATED GUSTS UP TO
35-40 MPH ALONG THE I-5 CORRIDOR.
THE OTHER THREAT FOR TODAY IS A SLIGHT CHANCE (15-20%) FOR
THUNDERSTORMS. LOOKING AT SATELLITE IMAGERY AS OF 11:30 AM,
CONDITIONS ARE CLEARING UP BEHIND THE FRONT ABOUT 75 MILES
OFFSHORE. IT APPEARS THERE'S SUBSIDENCE BEHIND THE FRONT WITH A
LOT OF DRY AIR. EVEN FURTHER BEHIND THIS POCKET OF DRY AIR
AROUND 180 MILES OFFSHORE, WE START TO SEE SOME INSTABILITY WITH
POPCORN CUMULUS CLOUDS. HOWEVER, RADAR CURRENTLY SHOWS NO
INDICATION OF THUNDERSTORMS IN THAT POST-FRONTAL REGION
OFFSHORE. LOOKING AHEAD AT THIS AFTERNOON ONCE WE TURN POST-
FRONTAL, IF WE GET ENOUGH CLEARING AND HEATING TODAY, WE COULD
SEE SOME ISOLATED THUNDERSTORMS POP-UP. IT WILL ULTIMATELY
DEPEND ON HOW MUCH HEATING WE GET. IF WE DON'T CLEAR OUT UNTIL
LATE THIS AFTERNOON OR EVENING, THEN CONFIDENCE FOR
THUNDERSTORMS WILL BE LOW. IF A THUNDERSTORM DOES PASS OVER AN
AREA, IT MAY PRODUCE LIGHTNING, HEAVY DOWNPOURS, GUSTY ERRATIC
WINDS, SMALL HAIL, AND/OR A FUNNEL CLOUD.
TOMORROW, THE UPPER-LEVEL LOW ASSOCIATED WITH TODAY'S SYSTEM
WILL MOVE OVERHEAD OF THE PACIFIC NORTHWEST. THIS WILL LEAD TO
COOLER TEMPERATURES ALOFT AND INCREASE ATMOSPHERIC INSTABILITY.
HREF GUIDANCE IS SHOWING MUCAPE VALUES ANYWHERE BETWEEN 100-500
J/KG ACROSS THE REGION TOMORROW. THIS INSTABILITY, ALONG WITH
GOOD LIFT AND MOISTURE FROM THE OVERALL UPPER-LEVEL LOW, WILL
SUPPORT A 20-30% CHANCE FOR THUNDERSTORMS THURSDAY
AFTERNOON/EVENING. EXPECT THE SAME IMPACTS LISTED ABOVE FOR ANY
PASSING THUNDERSTORMS. AGAIN, WITH EVEN COOLER AIR ALOFT ON
THURSDAY, AN ISOLATED COLD-CORE FUNNEL CLOUD CAN'T BE RULED OUT
(5-10% CHANCE). BY FRIDAY, THE UPPER-LEVEL LOW CONTINUES TO SIT
OVERHEAD, MAINTAINING CHANCES FOR LINGERING SHOWERS AND ANOTHER
15-20% CHANCE FOR AFTERNOON THUNDERSTORMS.
AS MENTIONED BEFORE, THIS SYSTEM IS A SOAKER AND IS BRINGING THE
FIRST SUBSTANTIAL RAINFALL OF THE SEASON. CHANCES FOR 48-HOUR
RAIN TOTALS EXCEEDING 1 INCH BETWEEN 5 AM WEDNESDAY AND 5 AM
FRIDAY ARE 85-95+% ALONG THE COAST, AND 50-75% ACROSS INTERIOR
VALLEYS INCLUDING THE I-5 CORRIDOR. WHILE THIS WET WEATHER WON'T
BE A "FIRE SEASON ENDER," IT WILL DEFINITELY SLOW DOWN FIRE
SEASON. -10
LONG TERM...SATURDAY THROUGH TUESDAY
OVER THE WEEKEND, THE
MAJORITY OF ENSEMBLE MEMBERS CONTINUE TO SHOW BROAD UPPER-LEVEL
TROUGHING OVER THE PACIFIC NORTHWEST. HOWEVER, THERE IS
UNCERTAINTY WITH WHETHER OR NOT WE REMAIN DRY OR CONTINUE WITH
LINGERING SHOWERS. WHILE 60% OF ENSEMBLE MEMBERS SUGGEST SHOWERS
CONTINUING OVER THE REGION SATURDAY-SUNDAY, THE OTHER 40% KEEP
US DRY. WHAT WE CAN SAY WITH HIGHER CONFIDENCE IS THAT THIS
UPPER-LEVEL LOW WILL MAINTAIN BELOW-AVERAGE 500 MB HEIGHTS AND
KEEP HIGH TEMPERATURES SLIGHTLY COOLER THAN AVERAGE FOR THIS
TIME OF YEAR. EARLY NEXT WEEK, THE MAJORITY OF ENSEMBLE MEMBERS
SHOW THE UPPER LOW WEAKENING AND BEGINNING TO MOVE EASTWARD.
THIS WOULD FAVOR DRIER CONDITIONS, BUT THERE REMAINS UNCERTAINTY
WITH HOW MUCH HIGH PRESSURE WILL RE-BUILD OVER OUR AREA, AND
HOW WARM/DRY WE GET. -10
AVIATION...THROUGH 06Z FRIDAY
RAIN HAS MOSTLY STOPPED ACROSS
THE AREA AS OF 05Z THU, HOWEVER EXPECT SHOWER ACTIVITY TO INCREASE
TOWARDS 08-13Z THU AS POST-FRONTAL SHOWERS DRIFT NORTHEASTWARD
INTO THE AIRSPACE. RAIN SHOWERS WILL GRADUALLY RETURN FROM NORTH
TO SOUTH, WITH THE LATEST ARRIVAL AROUND 13Z THU AT KEUG. ANY
STRONGER SHOWERS COULD TEMPORARILY KNOCK CONDITIONS BACK TO MVFR
OR LOWER THROUGH THURSDAY MORNING. PROBABILISTIC GUIDANCE
CURRENTLY SUGGESTS A 15-40% CHANCE OF MVFR CONDITIONS AT ANY GIVEN
HOUR DURING THE TAF PERIOD. ADDITIONALLY, THERE IS A 20-35%
CHANCE FOR THUNDERSTORMS THURSDAY AFTERNOON AT ALL TERMINALS, WITH
THE HIGHEST CHANCES ALONG THE COAST. ANY THUNDERSTORMS THAT
DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE LIGHTNING, SMALL HAIL,
AND GUSTY/ERRATIC WINDS.
SOUTHERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD, EXPECTED TO
RAMP UP TO AROUND 9-15 KT SUSTAINED WINDS WITH GUSTS AROUND 20-25
KT BETWEEN 08-23Z THU. WINDS WILL WEAKEN BEYOND 00Z FRI AND
POTENTIALLY SHIFT MORE SOUTHWESTERLY AT SOME TERMINALS.
KPDX AND APPROACHES...EXPECT RAIN SHOWERS AND VFR CONDITIONS TO
CONTINUE THROUGH THE TAF PERIOD. THERE IS A 10-30% CHANCE OF MVFR
CIGS BETWEEN 09-23Z THU, WITH THE HIGHEST CHANCES AROUND 12-17Z
THU. EXPECT AN ISOLATED THUNDERSTORM THREAT THURSDAY AS WELL,
MAINLY DURING THE AFTERNOON HOURS (MOST LIKELY BETWEEN 17Z THU AND
00Z FRI). ~12
MARINE
CURRENT SEAS AROUND 9-11 FT AT 8-10 SECONDS WILL
CONTINUE INTO THURSDAY AS A FRESH WEST/NORTHWEST SWELL OVERNIGHT
INTO THURSDAY MAINTAINS CONDITIONS. DUE TO THE CONTINUED SEA
STATE AND BREEZY WINDS, A SMALL CRAFT ADVISORY IS IN EFFECT
THROUGH THURSDAY AFTERNOON INTO THE EVENING. THERE'LL ALSO BE
15-30% CHANCE FOR THUNDERSTORMS TONIGHT THROUGH THURSDAY WITH THE
BEST RELATIVE CHANCES THURSDAY AFTERNOON. ANY OF THESE STORMS WILL
BE CAPABLE OF PRODUCING GUSTY/ERRATIC WINDS, SMALL HAIL, AND
LIGHTNING.
WHILE RELATIVELY ACTIVE WEATHER WITH LINGERING RAIN SHOWERS WILL
CONTINUE INTO THE WEEKEND, MARINE CONDITIONS WILL SUBSIDE BY
FRIDAY WITH SEAS HOLDING IN THE 4-6 FT RANGE BY FRIDAY AFTERNOON.
SIMILAR CONDITIONS PERSIST INTO EARLY NEXT WEEK WHILE WINDS
OCCASIONALLY GUST TO 15-20 KNOTS. ~12/99
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 PM PDT THURSDAY FOR PZZ210-251-252-
271-272.
SMALL CRAFT ADVISORY UNTIL 11 PM PDT THURSDAY FOR PZZ253-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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